The attempt failed with response code 504: exchum.lynclab.local.Request Target: [DefaultUM@exchum.company.local], Call Id: [9f9a3df33d2544a9a22ff2c17feedcb5].Failure occurrences: 4, since 10/12/2013 08:36:55 PM.Cause: An attempt to route to an Exchange UM server failed because the UM server was unable to process the request or did not respond within the allotted time.Resolution:Check this server is correctly configured to point to the appropriate Exchange UM server. Also check whether the Exchange UM server is up and whether it in turn is also properly configured.”

Like this:

I recently set up Lync 2010 at our offices and ran into a snag with Exchange 2010 SP2 UM voice mail integration. The symptom was the following error in Exchange 2010 UM:

The following UM IP gateways did not respond as expected to a SIP OPTIONS request.

Additional symptoms were that Lync client are unable to call voice mail and users are unable to leave a message for Lync users.

The Culprit

There are 2 possibilities here…#1The UM IP gateway in Exchange 2010 which is set up by running the ExchUCUtil.ps1 script doesn’t have a port listed in the configuration. This can be viewed by running:

Get-UMIPGateway | fl

Resolution

Run Set-UMIPGateway -Port 5061

#2The certificate assigned to the Exchange UM Server Role was not using its own FQDN as the Subject Name (SN), instead the SN was mail.domain.com. Interestingly this was working perfectly well before when we were on SP1…

ResolutionRe-issued a cert with the FQDN of the UM server as the subject name.

Like this:

After Googling this one “stukkend” (my SA buddies will know what I mean), I finally resorted to making a number of calls to get down to the actual atatchment size – cross referenced that with the math and came up with the answers.

Firstly it is worthy of note that the actualy size will depend on the following three factors:

the message duration

the audio codec used

the audio storage format

UM uses either WMA, GSM 6.10 and PCM for creating the voicemail files.WMA is always delivered as a .wma file and the GSM and PCM is delivered as .wav

Comparing the formats.

Format

Bytes per 10 seconds

30 Second

60 seconds

Description

PCM

160,000

156 KB

937 KB

Highest Quality, largest file size

GSM

16,000

48 KB

96 KB

Widely supported

WMA

(Default)

11,000

39 KB

65 KB

Most compressed. The WMA format has a much larger header section than WAV (about 7K compared to less than 100 bytes) WMA files become smaller than GSM from 15 seconds and up.

The bottom line…I generally use GSM since not all devices and apps support WMA. Usually I allow for approximatly 100 KB per minute of voicemail.Now for the tricky bit, how much voicemail to cater for?According to Forbes (and chatting to many folks over the years…) the average person gets around 2 voicemails per day. Most voicemails are around the 30 second mark in duration (or less)Calculation is thus approximatly 1 minute of voicemail per day per user.Using GSM, thats about 100 KB per day per user, 3 MB per month for each user and thus 36 MB per year.Is that all? On average yes…there are exceptions, very LARGE ones as this is based on users who actually attempt to answer calls.